Rhodobacterium Chromatium okenii is very abundant in the upper mud layer in Simmelried. In my other sampling sites I could not detect it so far. The motile cells collect at the bottom of the collection vessel after some time and form a reddish layer there. This can be observed especially well in vessels with a pointed bottom. The species is easily identified by its color, flagellum, and typical backward swimming style. The flagellum thus pushes the cell and does not pull it. The globules in the cells are elemental sulfur, which is formed during the oxidation of hydrogen sulfide (H₂S) with oxygen (O₂) to water (H₂O), sulfur (S) and sulfuric acid (H₂SO₄).